Grandfather to-be smokes, what effects could this have on my baby?

It's bad to let baby to inhale 2nd hand smoke. Even if your father smoke outside away from the house, the smoke chemical residuals will still stuck on his hair and clothes. Thus, it is best to advise your father to quit smoking and if this is not workable you might want to consider to shift out from the house as the impact of the smoke on the baby's respiratory is bad.